Mezzanines are frequently constructed in commercial or industrial establishments to increase the storage or production floor space. The typical mezzanine is supported above the foundation of the building by a series of vertical columns and includes a deck or supporting surface which is bordered by a railing. According to Federal requirements, the railing must be at least forty-two inches high and the openings between horizontal rails cannot exceed twelve inches. In the past the typical railing for a mezzanine has consisted of a series of vertical pipes which extend upwardly from the edge of the deck and cross-shaped or T-shaped fittings are located within each vertical pipe. Cylindrical rails are inserted through the horizontal openings of the cross-shaped and T-shaped fitting. With railings of this type, individual horizontal rails cannot be removed. For example, if it is desired to install or remove a relatively large piece of machinery or equipment from the mezzanine which would require the removal of a section of railing, it would be necessary to remove the entire railing, for individual sections cannot be disassembled. Thus, there has been a need for a railing construction in which individual rails can be removed from the railing.